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0000-0003-1813-4042
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James Cook University
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Publisher: Wiley
Date: 17-09-2021
DOI: 10.1002/AQC.3692
Abstract: One‐third of all elasmobranch species currently known to occur in Papua New Guinea are taken as bycatch in the Gulf of Papua trawl fishery. An ecological risk assessment was conducted on the 16 species of sharks and 23 species of rays caught by the fishery. Eight species were classified to be at low risk, 28 species were at medium risk while three species – Rhynchobatus palpebratus (eyebrow wedgefish), Carcharhinus coatesi (Australian blackspot shark) and Maculabatis astra (blackspotted whipray), all endemic to New Guinea and northern Australia – faced the highest level of risk from the fishery at current fishing levels. There is potential for more vessels to enter the fishery in future, which is likely to elevate the risk for a greater proportion of elasmobranch species. Ongoing monitoring of bycatch levels, supported by biological and ecological studies on frequently caught species, is required to assess and manage risk in the future. The development and use of trawl excluder devices or bycatch reduction devices in this fishery have the potential to reduce bycatch levels and reduce risk levels.
Publisher: Frontiers Media SA
Date: 06-09-2021
DOI: 10.3389/FCOSC.2021.719981
Abstract: The conservation of threatened elasmobranchs in tropical regions is challenging due to high local reliance on aquatic and marine resources. Due primarily to fishing pressure, river sharks ( Glyphis ) and sawfishes (Pristidae) have experienced large population declines in the Indo-Pacific. Papua New Guinea (PNG) may offer a refuge for these species, as human population density is low, and river shark and sawfish populations are thought to persist. However, few data are available on these species in PNG, and risk posed by small-scale fishers is poorly understood. This study observed elasmobranch catches in small-scale fisheries in riverine and coastal environments in the East Sepik (northern region), Gulf, and Western Provinces (southern region) of PNG. Surveys were conducted over a period of weeks to months in each region, during the dry season across seven field trips from 2017 to 2020. We observed a total of 783 elasmobranchs encompassing 38 species from 10 families. River sharks made up 29.4% of observations in the southern region, while sawfishes made up 14.8 and 20.3% in the northern and southern regions, respectively. River sharks were commonly caught by small-scale fishers in lower riverine environments in southern PNG, while sawfishes were generally less common and mainly observed through dried rostra. The primary threat to river shark and sawfish populations is their capture by small-scale fishers targeting teleosts for swim bladder. Persisting populations of river sharks and sawfishes indicate that PNG is the second known nation with viable populations of multiple species in the Indo-Pacific. However, populations are declining or at high risk of decline, and fisheries management and conservation are required to realize the potential of PNG as a long-term refuge.
Publisher: CSIRO Publishing
Date: 23-02-2022
DOI: 10.1071/MF21292
Abstract: Nursery areas are crucial for many elasmobranch species, providing advantages such as increased access to prey and reduced predation risk. This study investigated the trophic interactions of two juvenile stingray species within a coastal communal nursery using stable isotope analysis. Muscle, plasma and red blood cells s les were taken from the mangrove whipray Urogymnus granulatus and the cowtail stingray Pastinachus ater, and δ15N, δ13C and δ34S measured. Urogymnus granulatus had higher mean δ13C, δ15N and δ34S than P. ater. General linear models showed no significant trends between δ13C, δ15N or δ34S and body size or sex. Low isotopic niche overlap, combined with previous data on movement patterns, provided evidence of niche partitioning between stingrays that likely reflect differences in feeding grounds and prey selection. Despite the differences in feeding grounds and prey selection, previous studies showed that U. granulatus and P. ater share sand and reef flat areas for most of the day (~20 h). δ13C and δ34S values suggested that mangrove-derived carbon had little importance to stingrays’ diets in the study area. Results presented in this study bring new insights to the feeding ecology of two sympatric stingray species and their trophic interactions within a communal nursery area.
Publisher: Public Library of Science (PLoS)
Date: 31-10-2018
Publisher: Inter-Research Science Center
Date: 07-05-2020
DOI: 10.3354/MEPS13307
Abstract: Shark abundances are decreasing on many coral reefs, but the ecosystem effects of this loss are poorly understood. Rays are a prevalent mesopredator in tropical coral reef ecosystems that are preyed upon by top predators like sharks. Studies have suggested reduced predator abundances lead to increases in mesopredator abundance (mesopredator release). We examined the relationship between top predator abundances and the abundance and behaviour of 2 small benthic ray genera using baited remote underwater video systems (BRUVS) across 6 countries. Where predators were more abundant, 2 genera of small benthic rays were sighted less often, possibly because of lower abundances. Small ray behaviour was also significantly affected by predator abundance. In iduals of focal ray species visited BRUVS significantly fewer times at sites with higher predator abundances. Where predators were less abundant, rays spent significantly more time in the video frame, and were more likely to feed from bait bags. In addition to predator abundance, small ray presence was significantly influenced by reef relief and depth. Neotrygon spp. were more abundant on deeper, lower relief habitats, while Taeniura spp. were more prevalent in reef-associated shallow, high relief habitats. Overall, this study found that predator abundance had a significant effect on small benthic ray abundance and behaviour in the presence of BRUVS. Results demonstrate that changes in both abundance and behaviour associated with predator loss may make the interpretation of phenomenon like mesopredator release more difficult to identify unless behavioural effects are considered.
Publisher: Wiley
Date: 23-09-2020
DOI: 10.1002/AQC.3457
Publisher: CSIRO Publishing
Date: 11-02-2022
DOI: 10.1071/MF21212
Abstract: Assessing the feeding patterns of sharks provides insight into ecological interactions. Three coastal sharks are common by-catch in the Gulf of Papua prawn fishery in Papua New Guinea. The diets of Carcharhinus coatesi (n = 122), Rhizoprionodon acutus (n = 83) and Rhizoprionodon taylori (n = 177) were assessed using stomach content analysis. Teleosts, crustaceans and molluscs were the main prey. Percentage frequency of occurrence (%FO) and percentage frequency by number (%N) were computed to describe dietary compositions. Non-metric multidimensional scaling and Morisita Index determined the level of feeding overlap. Rhizoprionodon taylori was a generalist feeder having the broadest diet, R. acutus was the most selective feeder, preying predominantly on teleosts and C. coatesi consumed the greatest proportion of crustaceans that increased with size. The pairwise ANOSIM tests showed significant difference in dietary compositions of R. acutus and R. taylori (P = 0.1%, R = 0.318) and R. acutus and C. coatesi (P = 0.1%, R = 0.589), which indicate potential resource partitioning. Further work should aim to adequately characterise diets, improve prey identification and investigate spatial and temporal resource use patterns. Understanding ecological processes informs ecosystem approaches fisheries management.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/PCV24N1_ED
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/MF19048
Abstract: GPS telemetry provides high-accuracy spatial data on animal movement however, it has rarely been used with benthic organisms, such as stingrays, because of their irregular surfacing behaviour or bottom-dwelling habits. This study evaluated the use of towed-float GPS tags to assess movements of juvenile stingrays, with active tracking performed simultaneously for comparison. Four juvenile Urogymnus granulatus in iduals (2 females and 2 males average 32.2-cm disc width) were tracked in April 2016. In iduals travelled 1332.15±269.58m south-east across Pioneer Bay at an average speed of 6.87mmin–1 in 3.7h. Stationary tests demonstrated that the quality of the data obtained by towed-float GPS tags could not be matched by active, acoustic or ARGOS telemetry, reaching, on average, 99% of successful fixes and & -m accuracy. Location error varied significantly based on the number of satellites detected, with error decreasing as the satellite number increased. This study demonstrated the potential of towed-float GPS telemetry for high-resolution assessment of movement patterns and habitat use of juvenile stingrays in shallow coastal water. If well applied, this technique can increase our knowledge of juvenile stingray ecology and their essential habitats.
Publisher: Inter-Research Science Center
Date: 24-07-2012
DOI: 10.3354/MEPS09722
Publisher: Public Library of Science (PLoS)
Date: 27-02-2020
Publisher: Elsevier BV
Date: 08-2022
Publisher: Wiley
Date: 23-02-2016
DOI: 10.1111/FAF.12154
Publisher: Springer Science and Business Media LLC
Date: 07-01-2017
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/MF13017
Abstract: Inadequate life-history information can compromise management of shark populations. The present study examined the life history of blacktip reef sharks (Carcharhinus melanopterus) from north-eastern Australia with predictions that they would show life-history patterns similar to those of other reef sharks species. Age and growth estimates were derived from vertebrae and five growth models. Males were 543–1390 mm total length (LST) and females were 514–1600 mm LST. Longevity was 10 years (males) and 15 years (females). Chemical marking confirmed annual band pair deposition but indicated probable age underestimation of large in iduals. The logistic model was preferred (second-order Akaike information criterion (AICc) weight 0.7536), with growth parameter estimates of length at birth (L0) = 617 mm LST asymptotic length (L∞) = 1585 mm LST k (from logistic model) = 0.251 year–1. Males matured at 4.2 years (1050 mm LST) and females at 8.5 years (1335 mm LST), although further verification is needed. Mating and parturition occurred in summer and autumn, females having three or four pups per litter. Data were inconclusive in determining reproductive periodicity. These data contribute to the species management and conservation and suggest that the species may be sensitive to fishing pressure and habitat loss. The study also demonstrated potential complications in using vertebrae to estimate age and growth of chondrichthyan fishes.
Publisher: CSIRO Publishing
Date: 2023
DOI: 10.1071/PC22048
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/MF10142
Abstract: Human values, perceptions, attitudes and interactions with the natural environment have been found to change over time, with social and economic information used to inform management decisions and actions. Content analysis is applied here to a 53-year long collection of the popular e magazine, SportDiving, to identify recreational ers’ experiences with regard to sharks and rays, the Great Barrier Reef (GBR) and marine protected areas (MPAs). This analysis suggests there has been a ersification of er activities with the emergence of passive-observational activities such as SCUBA ing. Attitudes towards sharks and rays have changed significantly, with recreational ers changing from a group that could be described as adventure-seeking hunters to a group that can be described as nature-appreciating observers, suggesting an increase in conservation awareness. The GBR continues to be a highly regarded e destination, with ers perceiving positive effects of protection within MPAs. However, declines in the abundance of large fish and sharks and rays were occasionally reported throughout the 53 year period. Collectively, these types of data can show changes in resource-use patterns, perceptions and attitudes and provide information that supplements scientific monitoring data. These data may be valuable where scientific data is scarce, historical records difficult to obtain, and where attitudinal change can significantly affect future resource use.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Springer Science and Business Media LLC
Date: 09-2021
Publisher: CSIRO Publishing
Date: 30-09-2021
DOI: 10.1071/PC20063
Abstract: Anthropogenic pressures have been increasing on shark and ray populations globally, and their conservation and management can be compromised by lack of information on their ersity and status of species. This study presents a desktop review of the sharks and rays of the Republic of Palau, drawing on citizen science, fisheries data and other scientific literature to document their ersity, economic and cultural values, and pressures affecting their populations. This account of Palau’s sharks and rays includes a preliminary assessment of risks based-on existing risk assessments, and their biological productivity. Records were found documenting 56 sharks and rays in Palau: 31 species are considered here as ‘confirmed and verified’, 10 species as ‘requires verification’, and 11 species listed as ‘plausible’. An additional two species are listed as ‘unlikely’, and two species is ‘unknown’ due to the taxonomy being unclear. The biological productivity analysis showed that the basking shark (Cetorhinus maximus) had the lowest productivity of Palau’s sharks and rays, while the blue shark (Prionace glauca) showed the highest productivity of species examined. Historically, fishing mortality presented the most significant threat to Palau’s sharks and rays, but recent conservation initiatives have the potential to significantly reduce this threat as large areas are closed to fishing following the full implementation of the Palau National Marine Sanctuary in 2020. Palau’s sharks have a wide range of social and cultural values and are important to tourism. This study presents a new synthesis and overview of available information including citizen science, but also highlights the need for further local taxonomic work and research.
Publisher: Elsevier BV
Date: 07-2017
Publisher: Springer Science and Business Media LLC
Date: 17-08-2018
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/MF16165
Abstract: Oceanic whitetip sharks (Carcharhinus longimanus) in the Western Central Pacific have been overfished and require improved assessment and management to enable planning of recovery actions. S les from 103 in iduals (70 males and 33 females 76.0–240- and 128–235-cm total length (TL) respectively) were used to estimate age, growth and maturity parameters from sharks retained by longline fisheries in Papua New Guinea. Back-calculation was used because of the low number of juveniles and a multimodel framework with Akaike’s information criterion corrected for small s le size (AICc) estimated growth parameters. The von Bertalanffy growth model provided the best fitting growth model for both sexes. Parameter estimates for males were: asymptotic length (L∞)=315.6cm TL growth coefficient (k)=0.059 year–1 and length at birth (L0)=75.1cm TL. For females, the parameter estimates were: L∞=316.7cm TL k=0.057 year–1 and L0=74.7cm TL. Maximum age was estimated to be 18 years for males and 17 years for females, with a calculated longevity of 24.6 and 24.9 years respectively. Males matured at 10.0 years and 193cm TL, whereas females matured at 15.8 years and 224cm TL. C. longimanus is a slow-growing, late-maturity species, with regional variation in life history parameters, highlighting increased vulnerability to fishing pressure in this region.
Publisher: Springer Science and Business Media LLC
Date: 27-02-2020
DOI: 10.1038/S41467-019-14051-Y
Abstract: Section Flavi encompasses both harmful and beneficial Aspergillus species, such as Aspergillus oryzae , used in food fermentation and enzyme production, and Aspergillus flavus , food spoiler and mycotoxin producer. Here, we sequence 19 genomes spanning section Flavi and compare 31 fungal genomes including 23 Flavi species. We reassess their phylogenetic relationships and show that the closest relative of A. oryzae is not A. flavus , but A. minisclerotigenes or A. aflatoxiformans and identify high genome ersity, especially in sub-telomeric regions. We predict abundant CAZymes (598 per species) and prolific secondary metabolite gene clusters (73 per species) in section Flavi . However, the observed phenotypes (growth characteristics, polysaccharide degradation) do not necessarily correlate with inferences made from the predicted CAZyme content. Our work, including genomic analyses, phenotypic assays, and identification of secondary metabolites, highlights the genetic and metabolic ersity within section Flavi .
Publisher: Springer Science and Business Media LLC
Date: 14-06-2016
Publisher: Wiley
Date: 13-05-2022
DOI: 10.1002/PAN3.10337
Abstract: Shark bites are of high public concern globally. Information on shark occurrence and behaviour, and of the effects of human behaviours, can help understand the drivers of shark‐human interactions. In Australia, a number of shark bite clusters occurred over the last decade. One of these took place in Cid Harbour the Whitsundays, Queensland, a region for which little was known about the shark community. Here, we describe and evaluate the research in response to that shark bite cluster. Fishing methods, acoustic and satellite tracking, and baited remote underwater video cameras (BRUVs) were used to identify the shark species using Cid Harbour, estimate relative abundance, and describe habitat use and residency. Side‐scan sonar and BRUVs were also used to assess prey availability. Recreational users were surveyed to understand human behaviour and their awareness and perceptions of ‘Shark Smart’ behaviours. This allowed shark occurrence and behaviour to be interpreted in the context of human behaviours in the Harbour. Eleven shark species were identified. Relative abundance was not unusually high, and residency in Cid Harbour was typically low. For ex le, 79% of acoustically tagged sharks visited the harbour on % days at liberty. Shark prey was available year‐round. Notably, anchored boats regularly conduct activities that can attract sharks (dumping food scraps, provisioning and cleaning fish). Alone, the methods used in this study had variable success, but combined they provided a large amount of complementary information. Including a social science component in the research response to the shark bite incidents allowed for a more holistic understanding of the Cid Harbour bite incidents. This study did not identify anything unusual about the shark community that could have contributed to the Cid Harbour shark bite cluster. However, the three incidents involved people bitten almost instantly after entering the water, which is unusual and suggests that feeding/attracting sharks to boats could have been a contributor and also that any species capable of biting humans could have been responsible. The eradication of activities that attract sharks to areas where people enter the water may reduce shark bite risk. Read the free Plain Language Summary for this article on the Journal blog.
Publisher: Springer Science and Business Media LLC
Date: 02-08-2019
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/MF19191
Abstract: This study provides the first detailed investigation of the catches of the shark longline fishery in Papua New Guinea. Fisheries observers collected data on shark catches from a total of 318 longline sets between May and June 2014, before its closure in July 2014. In all, 14694 sharks were recorded with a total estimated biomass of 439 tonnes (Mg). Eighteen species of sharks were recorded in the observer data, with the most dominant species being Carcharhinus falciformis, which constituted more than 90% of the total catches by both weight and number of in iduals. The level of observer misidentification was low (& %), which reflected the use of region-specific identification guides by well-trained fisheries observers. The most erse catches were in the Solomon Sea area, whereas catches in most other areas, particularly the Bismarck Sea areas, were less erse and more strongly dominated by C. falciformis. Size and sex ratios varied by species, highlighting the importance of obtaining species-level information from the fishery being investigated. Any consideration by fisheries managers to reopen this fishery needs to consider the effect this will have on the species targeted and the livelihoods of coastal fishers who also rely on the same resources.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/PC17012
Abstract: Sharks and rays are facing increasing anthropogenic pressure globally, including in the Pacific. However, data on their status and bio ersity are lacking for many Pacific Large Ocean Island States. This study aimed to construct a species checklist for the sharks and rays occurring in the Solomon Islands, review the human interactions with these species, and present a synthesis of their conservation status. Given the paucity of available data, a wide range of data sources were used including fisheries data, citizen science, and ethnobiological studies. Results were validated through a review process involving expert informants. Fifty sharks and rays were identified from the Solomon Islands, of which 20 are assessed as Vulnerable or Endangered on the IUCN Red List, 10 in the Convention on International Trade in Endangered Species, and 11 in the Convention for Migratory Species. The checklist also presents an eastwards range extension for the Endangered dwarf sawfish Pristis clavata. Fishing appears to be the main impact, though impacts from habitat loss and degradation are possible. This study provides a systematic synthesis and review of the biological ersity, uses, and cultural significance of Solomon Islands sharks and rays, and describes a process for assembling species checklists and reviews in data-poor contexts. However, this synthesis is based on limited information and a complete assessment of shark and ray status in the Solomon Islands will require primary fieldwork.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/PC18069
Abstract: Small-bodied coastal sharks are often caught as by-catch in fishing operations. Life-history information for these sharks is needed to ascertain the level at which these populations are potentially affected by fishing. This study determined the age, growth and maturity of Carcharhinus coatesi captured by prawn trawlers in the Gulf of Papua. Using vertebral aging and an information-theoretic multimodel approach, the von Bertalanffy growth model fit the data best parameters were L0=40.6cm±0.8, L∞=74.8cm±2.1, k=0.33year−1±0.06. Length-at-maturity analysis indicated that males reach maturity at L50=66.3cm (CI: 63.8, 71.4) and L95=71.6 (CI: 64.6, 74.2) cm while females matured at L50=71.4cm (CI: 61.5, 72.01) and L95=72.5cm (CI: 62.7, 74.0). Age-at-maturity estimates showed that both males (A50=5.1 years (CI: 4.6, 7.1), A95=6.4 years (CI: 5.1, 7.2)) and females (A50=5.3 years (CI: 3.5, 8.7), A95=7.4 years (CI: 3.6, 8.8)) reach maturity at about the same age. This study addresses the need for specific life-history information for a data-deficient species in a region that has remained relatively under-researched but in need of ongoing improvements to fisheries management.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Springer Science and Business Media LLC
Date: 09-05-2019
Publisher: Springer International Publishing
Date: 2020
Publisher: Springer Science and Business Media LLC
Date: 13-07-2007
Publisher: National Inquiry Services Center (NISC)
Date: 03-04-2015
Publisher: Frontiers Media SA
Date: 06-02-2018
Publisher: Springer Science and Business Media LLC
Date: 15-11-2022
DOI: 10.1007/S11160-022-09732-9
Abstract: Shark depredation is a complex social-ecological issue that affects a range of fisheries worldwide. Increasing concern about the impacts of shark depredation, and how it intersects with the broader context of fisheries management, has driven recent research in this area, especially in Australia and the United States. This review synthesises these recent advances and provides strategic guidance for researchers aiming to characterise the occurrence of depredation, identify the shark species responsible, and test deterrent and management approaches to reduce its impacts. Specifically, the review covers the application of social science approaches, as well as advances in video camera and genetic methods for identifying depredating species. The practicalities and considerations for testing magnetic, electrical, and acoustic deterrent devices are discussed in light of recent research. Key concepts for the management of shark depredation are reviewed, with recommendations made to guide future research and policy development. Specific management responses to address shark depredation are lacking, and this review emphasizes that a “silver bullet” approach for mitigating depredation does not yet exist. Rather, future efforts to manage shark depredation must rely on a erse range of integrated approaches involving those in the fishery (fishers, scientists and fishery managers), social scientists, educators, and other stakeholders.
Publisher: Public Library of Science (PLoS)
Date: 17-12-2020
DOI: 10.1371/JOURNAL.PONE.0244154
Abstract: Baited remote underwater video stations (BRUVS) are increasingly being used to evaluate and monitor reef communities. Many BRUVS studies compare multiple sites s led at single time points that may differ from the s ling time of another site. As BRUVS use grows in its application to provide data relevant to sustainable management, marine protected area success, and overall reef health, understanding repeatability of s ling results is vital. We examined the repeatability of BRUVS results for the elasmobranch community both within and between seasons and years, and explored environmental factors affecting abundances at two sites in Indonesia. On 956 BRUVS, 1139 elasmobranchs (69% rays, 31% sharks) were observed. We found consistent results in species composition and abundances within a season and across years. However, elasmobranch abundances were significantly higher in the wet season. The elasmobranch community was significantly different between the two sites s led, one site being more coastal and easily accessed by fishermen. Our results demonstrate that while BRUVS are a reliable and repeatable method for surveying elasmobranchs, care must be taken in the timing of s ling between different regions to ensure that any differences observed are due to inherent differences amongst s ling areas as opposed to seasonal dissimilarities.
Publisher: Springer Science and Business Media LLC
Date: 25-06-2019
DOI: 10.1038/S41598-019-45715-W
Abstract: The elasmobranch bycatch of the Gulf of Papua Prawn Fishery is investigated in detail for the first time. Fisheries observers collected data on the elasmobranch bycatch from a total of 403 trawl sets (1,273 hrs) in the Gulf of Papua. A total of 40 species of elasmobranchs were recorded ranging in size from a 12 cm disc width stingray to a 350 cm total length sawfish. High mortality rates were recorded ( %), attributed to the long trawl durations (up to 4 hours). The future inclusion of bycatch reduction devices would likely reduce the number of larger elasmobranchs being caught, based on evidence from the prawn trawl fisheries of northern Australia, and is being investigated by the PNG National Fisheries Authority. Differences in catch compositions were detected across the management zones as well as between the two monsoonal seasons (SE Monsoon and NW Monsoon). Increased monitoring and additional research is required and management plans should address the elasmobranch bycatch and in particular their high mortality rate.
Publisher: Wiley
Date: 03-2016
DOI: 10.1890/15-0457
Publisher: Wiley
Date: 22-12-2022
DOI: 10.1002/AQC.3754
Abstract: Shark‐like rays (Order Rhinopristiformes) are among the most threatened families of marine fish, yet little is known about their populations. These rays are normally taken as opportunistic catch in fisheries targeting other species and are thus poorly reported. One exception is the Indonesian tangle net fishery, which targets shark‐like rays. Market surveys of Muara Angke landing site in Jakarta, north‐western Java were conducted between 2001 and 2005, and the landed catch from the tangle net fishery was recorded (the Muara Angke landing site includes landings from more than one fishery). In total, 1,559 elasmobranchs (sharks and rays) were recorded, comprising 24 species of rays and nine species of sharks. The most abundant species landed were the pink whipray Pateobatis fai and the bottlenose wedgefish Rhynchobatus australiae , the latter being the main target species. Catch composition varied based on differences in species catchability and may also be indicative of localized declines. The fishery was highly selective for larger sized in iduals, while smaller size classes of many ray species, including the target species, were also caught in other Indonesian fisheries, resulting in fishing pressure across all age classes. The decline of tangle net vessels in the fishery and the potential shift in catch composition in the Indonesian tangle net fishery increase concerns about the status of shark‐like rays and stingrays in Indonesia.
Publisher: Wiley
Date: 05-08-2021
DOI: 10.1002/AQC.3678
Abstract: Sawfish (Pristidae) are considered to be among the most threatened families of elasmobranch (sharks and rays). There is a need to gather information on the status of poorly known sawfish populations to assist in global recovery initiatives. This study used interviews with local fishers to investigate the presence of sawfish in southern Papua New Guinea (PNG) and their interactions with and uses and values for small‐scale fishers. A range of sawfish size classes are still encountered throughout southern PNG, while juvenile largetooth sawfish Pristis pristis were additionally reported in the freshwater reaches of all rivers surveyed. Reports of large size classes in estuarine and marine environments provide an optimistic outlook that sawfish populations persist throughout southern PNG. Most fishers that catch sawfish retain them for various uses including consumption and for the sale of meat, fins and occasionally rostra. Negative population trends including decreases in catch frequency and/or size classes were reported by 66% of interviewees, with the largest declines being reported in the Kikori River. The increasing technical capacity of small‐scale fishers, their preference for gillnetting and the emerging market for teleost swim bladder (a high‐value fishery product) present a major ongoing threat to sawfish in southern PNG. Furthermore, the tendency of fishers to kill or remove rostra from entangled sawfish results in high fishing mortality regardless of any use by the fisher. This study indicates that considerable community engagement will be necessary to manifest any legislative actions or increased enforcement on international trade regulations for sawfish in PNG. This is due to traditional land and waterway ownership values throughout PNG and the local perception of sawfish as a traditional food resource rather than an animal of intrinsic bio ersity value as perceived by global conservationists. Future research should consider exploring culturally appropriate conservation initiatives that are likely to achieve engagement and participation from local fishers.
Publisher: Springer Science and Business Media LLC
Date: 21-04-2017
DOI: 10.1038/SREP46061
Abstract: Conservation and management of migratory species can be complex and challenging. International agreements such as the Convention on Migratory Species (CMS) provide policy frameworks, but assessments and management can be h ered by lack of data and tractable mechanisms to integrate disparate datasets. An assessment of scalloped ( Sphyrna lewini ) and great ( Sphyrna mokarran ) hammerhead population structure and connectivity across northern Australia, Indonesia and Papua New Guinea (PNG) was conducted to inform management responses to CMS and Convention on International Trade in Endangered Species listings of these species. An Integrated Assessment Framework (IAF) was devised to systematically incorporate data across jurisdictions and create a regional synopsis, and amalgamated a suite of data from the Australasian region. Scalloped hammerhead populations are segregated by sex and size, with Australian populations dominated by juveniles and small adult males, while Indonesian and PNG populations included large adult females. The IAF process introduced genetic and tagging data to produce conceptual models of stock structure and movement. Several hypotheses were produced to explain stock structure and movement patterns, but more data are needed to identify the most likely hypothesis. This study demonstrates a process for assessing migratory species connectivity and highlights priority areas for hammerhead management and research.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/MF17163
Abstract: In the central west Pacific region, silky sharks (Carcharhinus falciformis) are commonly taken in fisheries, forming up to 95% of incidental elasmobranch bycatch. The present study examined the life history of silky sharks (n=553) from Papua New Guinean waters. Age was analysed using sectioned vertebrae, and a multimodel approach was applied to the length-at-age data to fit growth models. Females ranged in length from 65.0- to 253.0-cm total length (TL), with the oldest estimated at 28 years. Males ranged in length from 68.4 to 271.3cm TL and were aged to a maximum of 23 years. The logistic model provided the best fitting growth parameter estimates of length at birth L0=82.7cm TL, growth coefficient g=0.14year–1 and asymptotic length L∞=261.3cm TL for the sexes combined. Females reached sexual maturity at 204cm TL and 14.0 years, whereas males reached maturity at 183cm TL and 11.6 years. The average litter size from 28 pregnant females was 8 (range of 3–13). The growth parameters and late ages of sexual maturation for silky sharks in the central west Pacific suggest a significant risk from fisheries exploitation without careful population management.
Publisher: Springer Science and Business Media LLC
Date: 10-2012
DOI: 10.1038/490176D
Publisher: The Royal Society
Date: 07-2021
Publisher: Inter-Research Science Center
Date: 18-02-2016
DOI: 10.3354/MEPS11545
Publisher: Wiley
Date: 12-03-2013
DOI: 10.1111/JFB.12057
Abstract: This study examined the characteristics of a blacktip reef shark Carcharhinus melanopterus population in turbid coastal habitats through a multi-year fishery-independent s ling and tag-recapture programme. Results revealed a highly structured population comprised almost entirely of juveniles and adult females with in iduals between 850 and 1050 mm total length effectively absent. Mature males were also rarely encountered with adult sex ratio highly biased towards females (female:male = 7:1). Mating scars were observed on adult females between December and April, and parturition was observed from December to March. Regression analysis showed that catch rates were significantly higher during the summer wet season between November and May. Recapture data suggested a highly resident population with a recapture rate of 21% and a mean recapture distance of 0·8 km. In addition, 33% of recaptured animals were captured multiple times, indicating long-term residency. Most recaptures were, however, of adults with few juveniles recaptured. Widespread s ling at the study site and in adjacent areas suggested that the population was highly localized to a specific bay. The bimodal and sex-segregated population structure observed here differs from previous reports for this species, and in combination with reproductive observations, suggests population structuring to facilitate reproductive and recruitment success. These data also highlight the potential ecosystem functions performed by coastal habitats in sustaining C. melanopterus populations.
Publisher: Oxford University Press (OUP)
Date: 2015
Publisher: Wiley
Date: 06-2010
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/PC140048
Abstract: There has been growing interest in engaging citizen scientists in the collection of environmental data to inform conservation efforts and decision making, and to augment formal monitoring programmes. Citizen scientists can collect data across large spatial and temporal scales that cannot be feasibly covered through traditional research and monitoring programmes. The ‘Porcupine Ray Hunt’ was a pilot study that engaged the Australian recreational SCUBA ing community in collecting information on the porcupine ray Urogymnus asperrimus, an easily identifiable but rare and poorly understood species. ‘Crowd sourcing’ of recreational ers was achieved by advertising the programme through ing publications, the internet, e-mail lists and social media (facebook and blogs). Dive clubs, e shops and research stations also advertised the project. Recreational ers were required to submit photographs and observations for verification and 29 new valid records were received. Submissions also included video footage of foraging and mating behaviour. The submissions received doubled the number of existing records on the species in Australia, identified distribution ‘hot spots’, provided a depth range for the species and extended the species’ range. In doing so, the project demonstrated the potential for citizen scientists to contribute valuable knowledge about rare species, addressing some of the knowledge gaps concerning the porcupine ray and providing preliminary data for future research.
Publisher: Cold Spring Harbor Laboratory
Date: 18-04-2019
DOI: 10.1101/608935
Abstract: Shark-like rays (Order Rhinopristiformes) are among the most threatened families of marine fish. Yet little is known about their populations, as these rays are normally taken as opportunistic catch in fisheries targeting other species and are thus poorly reported. One exception is the Indonesian tangle net fishery, which targets shark-like rays. Market surveys of Muara Angke landing site in Jakarta, north-western Java (including one frozen shipment from Benoa Harbour, Bali), were conducted between 2001 and 2005, and recorded landed catch for this fishery. Recent catch data from Indonesian Capture Fisheries (2017 – 2018) were also examined to provide contemporary information about landed catch. 1,559 elasmobranchs (sharks and rays) were recorded, comprised of 24 species of rays and nine species of sharks. The most abundant species landed were the pink whipray Pateobatis fai and the bottlenose wedgefish Rhynchobatus australiae , the latter being the main target species. Catch composition varied based on differences in species catchability and may also be indicative of localized declines. The fishery was highly selective for larger sized in iduals, however smaller size classes of target species were also caught in other Indonesian fisheries resulting in fishing pressure across all age classes. Evidence of substantial declines in global landings of wedgefish species, and the observed shift in catch composition in the Indonesian tangle net fishery, increases concerns about the status of shark-like rays and stingrays in Indonesia.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/PC18088
Abstract: Citizen science provides valuable information about species distributions. The Shark Search Indo-Pacific project received photographs of devil rays (Mobula spp.) from the Solomon Islands that were identified as Kuhl’s devil ray (Mobula kuhlii). These records represent new knowledge about the range and distribution of a poorly known species in an unders led region.
Publisher: Wiley
Date: 15-07-2020
Publisher: Inter-Research Science Center
Date: 14-05-2018
DOI: 10.3354/MEPS12545
Publisher: Informa UK Limited
Date: 16-06-2021
Publisher: Public Library of Science (PLoS)
Date: 08-04-2016
Publisher: Elsevier BV
Date: 10-2019
Publisher: Wiley
Date: 27-07-2022
DOI: 10.1111/COBI.13962
Abstract: In Southeast Asia, elasmobranchs are particularly threatened. We synthesized knowledge from the peer‐reviewed and gray literature on elasmobranchs in the region, including their fisheries, status, trade, biology, and management. We found that 59% of assessed species are threatened with extinction and 72.5% are in decline rays were more threatened than sharks. Research and conservation is complicated by the socioeconomic contexts of the countries, geopolitical issues in the South China Sea, and the overcapacity and multispecies nature of fisheries that incidentally capture elasmobranchs. The general paucity of data, funds, personnel, and enforcement hinders management. Reduced capacity in the general fishery sector and marine protected areas of sufficient size (for elasmobranchs and local enforcement capabilities) are among recommendations to strengthen conservation.
Publisher: Wiley
Date: 02-04-2013
DOI: 10.1002/AQC.2349
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/MF20078
Abstract: Stingrays are a erse and widespread group of elasmobranchs. Despite their ecological and economical importance, many aspects of stingray ecology remain poorly understood. Few studies have examined fine-scale movements of juvenile stingrays within nursery areas. This study aimed to examine diel movement patterns in juvenile mangrove whiprays (Urogymnus granulatus) by using towed-float GPS telemetry within a reef flat habitat of the Great Barrier Reef. Juvenile mangrove whiprays travelled distances from 394 to 2189m, moving at a rate (mean±s.e.) of 3.97m min–1±2.5 during tracking periods ranging from 1.35 to 9h. Movements of juvenile mangrove whiprays were influenced by tidal height and diel period. In iduals chose more direct paths during outgoing and incoming tides and their activity space was significantly larger during the day than at night-time. In iduals showed preference for mangrove areas during high tides, which was likely to reduce predation risk. Our findings have established the use of the towed-float GPS telemetry as an effective tool to assess short-term movement patterns and habitat use of juvenile stingrays, as well as highlighted how juvenile mangrove whiprays use reef-flat environments.
Publisher: Wiley
Date: 28-12-2023
DOI: 10.1111/COBI.13917
Abstract: Marine protected areas (MPAs) are key tools in addressing the global decline of sharks and rays, and marine parks and shark sanctuaries of various configurations have been established to conserve shark populations. However, assessments of their efficacy are compromised by inconsistent terminology, lack of standardized approaches to assess how MPAs contribute to shark and ray conservation, and ambiguity about how to integrate movement data in assessment processes. We devised a conceptual framework to standardize key terms (e.g., protection , contribution , potential impact , risk , threat ) and used the concept of portfolio risk to identify key attributes of sharks and rays (assets), the threats they face (portfolio risk), and the specific role of MPAs in risk mitigation (insurance). Movement data can be integrated into the process by informing risk exposure and mitigation through MPAs. The framework is operationalized by posing 8 key questions that prompt practitioners to consider the assessment scope, MPA type and purpose, range of existing and potential threats, species biology and ecology, and management and operational contexts. Ultimately, MPA contributions to shark and ray conservation differ according to a complex set of human and natural factors and interactions that should be carefully considered in MPA design, implementation, and evaluation.
Publisher: Inter-Research Science Center
Date: 22-04-2013
DOI: 10.3354/MEPS10244
Publisher: Inter-Research Science Center
Date: 12-12-2019
DOI: 10.3354/MEPS13150
No related grants have been discovered for Andrew Chin.